Employing the 2002 household survey data in 9 provinces in East China，this paper examines
the effect of family structure on female and male labor force participation．Constructing regression models with instrument variables to correct for the endogeneity of family structure，our results indicate that intergenerational coresidence significantly increases female labor force participation and weekly working time，while it has no effect on male labor supply．A major reason is that coresidence help to reduce female housekeeping burden through their parents' assistance，which frees up time for work in labor market．These results suggest that decline in intergenerational coresidence in the past two decades could contribute to the more rapid decrease in female labor force participation in China．